CA1230626A - Molded case circuit breaker with movable upper electrical contact positioned by tension springs - Google Patents

Abstract

A molded case circuit breaker includes a movable upper electrical contact having a base por-tion with a slot formed therein for releasably re-ceiving a portion of an elongated spring biased lock-ing pin disposed in a rotatable cross bar of an oper-ating mechanism of the circuit breaker. The locking pin is biased in the slot by a pair of tension springs secured to the cross bar, enabling the upper electrical contact to move in unison with the cross bar. Upon the occurrence of a high level short cir-cuit or fault current of sufficient magnitude, the pin is displaced from the slot enabling the independ-ent rotational movement of the upper contact arm.
During such movement, an elongated leaf spring is downwardly deflected and then released by the base portion. Subsequently, the upper electrical contact is prevented from contacting the lower electrical contact by the engagement of the leaf spring with the base portion. A subsequent trip operation of the operating mechanism removes the latching feature of the leaf spring.

Description

I

1 51,006 MOLDED CASE CIRCUIT BREAKER WITH
MOVABLE UPPER ELECTRICAL CONTACT POSITIONED
BY TENSION SPRINGS

CROSS REFERENCE TO RELATED APPLICATIONS
The invention disclosed herein relates to molded case circuit breakers. The invention disclosed in the lot-lowing commonly assigned Canadian patent application also relates to molded case circuit breakers: Canadian patent application Serial No. 440,224~ filed November 2, 1983.
The following commonly assigned Canadian patent applications also relate -to molded case circuit breakers:
Serial No. 468,684, filed November 27, 1984 by Alfred E.
Meter and entitled Molded Case Circuit Breaker With An Aver-lured Molded Cross Bar For Supporting A Movable Electrical Contract Arm; Serial No. 469,801, filed December 11, 1984 by Robert H. Flick and Walter K. Hoffman and entitled Molded Case Circuit Breaker With Improved Operating Mechanism; and Serial No. 469,800, filed October 5, 1984 by Robert H. Flick and Walter K. Hoffman and entitled Molded Case Circuit Breaker With Movable Lower Electrical Contact.
BACKGROUND OF THE INVENTION
A. Field of the Invention The device of the prevent invention generally relates to molded case circuit breakers and, more particularly, to electrical contacts used in such circuit breakers.

':

2 51, 006 B. Description of the Prior Art Circuit breakers and, more particularly, molded case circuit breakers are old and well known in the prior art. Examples of such devices are disclosed in United States Patents 3,525,959, issued August 25, 1970; 3,614,865, issued October 26, 1971; 3,815,059, issued June 4, 1974; 3,863,042, issued January 28, 1975; 4,077,025, issued February 28, 1978;
and 4,166,205, issued August 28, 1979. In general, prior art molded case circuit breakers have been provided with movable contact arrangements and operating mechanisms designed to provide protection for an electrical circuit or system against electrical faults, specifically, electrical overload conditions, low level short circuit or fault current conditions, and, in some cases, high level short circuit or fault current conditions. Prior art devices have utilized a trip mechanism for controlling the movement of an over-center toggle mechanism to separate a pair of electrical contacts upon an overload condition or upon a short circuit or fault current condition.
Such trip mechanisms have included a bimetal movable in response to an overload condition to rotate a trip bar, resulting in the movement of the over-center toggle mechanism to open a pair of electrical circuit breaker contacts. Such prior art devices have also I

I

3 51,006 utilized an armature movable in response to the flow of short circuit or fault current to similarly rotate the trip bar to cause the pair of contacts to spear-ate. At least some prior art devices use blow-apart contacts to rapidly interrupt the flow of high level short circuit or fault currents.
While many prior art devices have provided adequate protection against fault condition in an electrical circuit, a need exists for dimensionally small molded case circuit breakers capable of fast, effective and reliable operation and, more specific-ally, for a compact, movable upper electrical contact capable of rapid movement away from an associated lower electrical contact during high level short air-cult or fault current conditions, such movement being independent of and in advance of the sequencing Of the operating mechanism of the circuit breaker through a trip operation.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a new and improved circuit breaker.
Another object of the present invention is to provide a new and improved molded case circuit breaker having a compact, movable upper electrical contact capable of rapidly separating from an assess-axed lower electrical contact during high level short circuit or fault current conditions.
Another object of the present invention is to provide a new end improved molded case circuit breaker having a movable upper electrical contact yield ably biased into engagement with a portion of the operating mechanism of the circuit breaker to cause the upper electrical contact to move in unison with what portion during normal operation of the air-cult breaker while enabling the independent movement of the upper electrical contact in response to high level short circuit or vault current conditions.

4 51,006 Briefly, the present invention relates to a molded case circuit breaker having a movable upper electrical contact that occupies a relatively small amount of space while providing fast, effective end reliable operation in protecting an electrical air-cult or system from electrical fault conditions. The upper electrical contact includes a base portion have in a generally J-shaped slot formed therein for no-ceiling a portion of an elongated, spring biased locking pin. The pin is disposed against the forward edges of a pair of elongated, spaced apart, aligned slots or apertures formed in a rotatable cross bar ox an operating mechanism of the circuit breaker. An upper edge of the slot in the base portion contacts the outer periphery of the pin at a distance less than halfway along the diameter of the pin to enable the disengagement of the upper electrical contact from the pin upon the occurrence of a high level short circuit or fault current condition.
Normally, the pin is both kept in engage-mint with the forward surfaces of the elongated slots by a pelf of tension springs secured to the cross bar and a least partially roused within the slot in the base portion to enable movement ox the upper electrical contact in unison with the cross bar Upon top occurrence of a high level short circuit or fault current of sufficient magnitude, the resultant high magnetic repulsion forces are suffix client to rapidly move the upper edge of the slot in I the base portion along the outer periphery of the pin, rearwardly displacing the pin against the force of the tension springs and disengaging the base port lion from the pin, thereby enabling the substantially unimpeded rotation of the upper electrical contact.
During the unimpeded rotation of the upper electrical contact, a lower contact edge of the slot in the base portion can downwardly deflect and then release the I

- 5 51,006 free end of an elongated leaf spring secured to the base of the circuit breaker. Subsequently, the upper electrical contact is maintained spaced apart from an associated lower electrical contact of the circuit breaker by the leaf spring.
A subsequent trip operation of the operate in mechanism removes the latching feature of the leaf spring. During the trip operation, the upper electrical contact is forced against a fixed stop of the circuit breaker by the rotating cross bar to bring the pin into engagement with a contoured surface of the base portion of the upper electrical contact. By following along the contoured surface, the pin is deflected rearwardly until it passes the upper edge of the slot formed in the base portion, at which time it snaps forward into that slot to reset the upper electrical contact and the cross bar for movement in unison The above and other objects and advantages and novel features of the present invention will be come apparent from the following detailed description of the preferred and alternative embodiments of a molded case circuit breaker illustrated in the accom-paying drawing wherein:
Fig 1 is a top plan view of a molded case circuit breaker;
Fig. 2 is a side elevation Al view of the device of Fig. l;
Fig. 3 is an enlarged, cross sectional view of the device of Fig. 1 taken along line 3-3 of Fig.
1, depicting the device in its C10SED and BLOWN-OPEN
positions;
Fig. 4 is an enlarged, plan sectional view of the device of Fig. 1 taken along line 4--4 ox Fig.
.

I

6 51,006 Fig. 5 is an enlarged, cross sectional view of the device of Fig. l taken along line S-5 of Fig.
3;
Fig. 6 is an enlarged, fragmentary, cross sectional view of the center pole or phase of the device of Fig. 1 taken along line 6-6 of Fig. 3;
Fig. 7 is an enlarged, cross sectional view of the device of Fig. l taken along line 7-7 of Fig.
3;
Fig. 8 is an enlarged, fragmentary, cross sectional view of the center pole or phase of the device of Fig. l taken along line 8-8 of Fig. 3;
Fig. 9 is an enlarged, fragmentary, plan view of the center pole or phase of the device of Fig. l taken along line 9-9 of Fig. 3;
Fig. 10 is an enlarged, fragmentary, plan view of the center pole or phase of the device of Fig. 1 taken along line 10-10 of Fig. 3;
Fig. if is an enlarged, fragmentary, cross sectional view of a portion of the device of Fig. 1 taken along line 11-ll of Fig. 3;
Fig. 12 is an enlarged exploded, perspec-live view of portions of the operating mechanism of the device of Fig. l;
Fig. 13 is an enlarged, perspective view of the trip bar of the device of Fig. 1;
Fig. 14 is an enlarged, fragmentary cross sectional view of the center pole or phase of the device of Fig. l, depicting the device in its OPEN
position;
Fig. 15 is an enlarged, fragmentary, cross sectional view of the center pole or phase of the device of Fig. l, depicting the device in its TRIPPED position;
Fig. 16 is an enlarged, fragmentary, cross sectional view of an alternative embodiment of the ,

7 51,006 device of Fig. 1, depicting the device in its CLOSED
and BLOWN-OPEN positions;
Fig. 17 is an enlarged, fragmentary, plan sectional view of the device of Fig. 16 taken along line 17-17 of Fig 16;
Fig. 18 is an enlarged, fragmentary, cross sectional view of the device ox Fig. 16, depicting the device in its TRIPPED position;
Fig. 19 is an enlarged, fragmentary, cross sectional view of an alternative embodiment of the device of Fig. 1, depicting the device in its CLOSED
and BLOWN-OPEN positions;
Fig. 20 is an enlarged, fragmentary, plan sectional view of the device of Fig. 19 taken along line 20-20 of Fig. 19;
Fig. 21 is an enlarged, fragmentary, cross sectional view of the device of Fig. 19, depicting the device in its TRIPPED position;
Fig. 22 is an enlarged, fragmentary, cross sectional view of an alternative embodiment of the device of Fig. 1, depicting an alternative adjustable stationary lower electrical contact;
Fig. 23 is an enlarged, fragmentary cross sectional view of the device of Fig. 22 taken along line 23-23 ox Fig. 22;
Fig. 24 is an enlarged, perspective view of the electrical contact of Fig. 22;
Fig. 25 is an enlarged, fragmentary, cross sectional view of an alternative embodiment of the device of Fig. 1, depicting an alternative stationary lower electrical contact; and Fig. 26 is an enlarged, perspective view of the electrical contact of Fig. 25.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawing and initially to Figs. 1-15, there is illustrated a new and improve molded case circuit breaker 30 constructed in accord-~g3~6

- 8 51,006 ante with the principles of the present invention.
While the circuit breaker 30 is depicted and desk cried herein as a three phase or three pole circuit breaker, the principles of the present invention disk closed herein are equally applicable to single phase or other polyphase circuit breakers and to both AC
circuit breakers and DC circuit breakers.
The circuit breaker 30 includes a molded, electrically insulating, top cover 32 mechanically secured to a molded, electrically insulating, bottom cover or base 34 by a plurality of fasteners 36. A
plurality of first electrical terminals or line ton-finals AYE, 38B and 38C (Fig. 4) are provided, one for each pole or phase, as are a plurality of second electrical terminals or load terminals AYE, 40B and 40C. These terminals are used to serially electric-ally connect the circuit breaker 30 into a three phase electrical circuit for protecting a three phase electrical system.
The circuit breaker 30 further includes an electrically insulating, rigid, manually engage able handle 42 extending through an opening 44 in the top cover 32 for setting the circuit breaker 30 to its CLOSED position (Fig. 3) or to its OPEN position (Fig. 14). The circuit breaker 30 also may assume a BLOWN-OPEN position (Fig. I dotted line position) or a TRIPPED position (Fig. 15). Subsequently to being placed in its TRIPPER position, the circuit breaker 30 may be reset log further protective operation by moving the handle 42 prom its TRIPPED position (Fig.
15) past its OPEN position (Fig. 14). The handle 42 may then be left in its OPEN position (FIG. 14) or moved to its CLOSED position (Fig. 3), in which case the circuit breaker I is ready for further protect live operation. The movement of the handle 42 may be achieved either manually or automatically by a I; machine actuator. Preferably, an electrically in-

9 51,006 sulfating strip 46r movable with the handle 42, covers the bottom of the opening 44 and serves as an elect tribal barrier between the interior and the exterior of the circuit breaker 30.
As its major internal components, the air-cult breaker 30 includes a lower electrical contact 50, an upper electrical contact 52, an electrical arc chute 54, a slot motor 56, and an operating mechanism 58. The arc chute 54 and the slot motor 56 are con-ventional, per so, and thus are not discussed in de-tail hereinafter. Briefly, the arc chute 54 is used to divide a single electrical arc formed between separating electrical contacts 50 and 52 upon a fault condition into a series of electrical arcs, increase in the total arc voltage and resulting in a limiting of the magnitude of the fault current. The slot motor 56, consisting either of a series of generally U-shaped steel laminations encased in electrical in-solution or of a generally U-shaped, electrically insulated, solid steel bar, is disposed about the contacts 50 and 52 to concentrate the magnetic field generated upon a high level short circuit or fault current condition, thereby greatly increasing the magnetic repulsion forces between the separating electrical contacts 50 and 52 to vapidly accelerate the separation of electrical contacts 50 and 52. The rapid separation of the electrical contacts 50 and 52 results in a relatively high arc resistance to limit the magnitude of the fault current. Reference may be had to United States Letters Patent No. 3,815,059 for a more detailed description of the arc chute 54 and the slot motor 56.
The lower electrical contact 50 (Figs 3, 4 and 11) includes a lower, formed, stationary member 62 secured to the base 34 by a fastener 64, a lower movable contact arm 66, a pair of electrical contact compression springs 68, a lower contact biasing means I
lo 51,006 or compression spring 70, a contact 72 for physically and electrically contacting the upper electrical con-tact 52 and an electrically insulating strip 74 Jo reduce the possibility of arcing between the upper S electrical contact 52 and portions of the lower elect tribal contact 50. The line terminal 38B extending exteriorly of the base 34 comprises an integral end portion of the member 62. The member 62 includes an inclined portion AYE that serves as a lower limit or stop for the moving contact arm 66 during its blow-open operation; an aperture 62B overlying a recess 76 formed in the base 34 for seating the compression spring 70; and a lower flat section 62C through which the aperture 62B is formed. The flat section 62C may also include a threaded aperture 62D formed there-through for receiving the fastener 64 to secure the stationary member 62 an thus the lower electrical contact 50 to the base 34. The stationary member 62 includes a pair of spaced apart, integrally formed, upstanding, generally curved or U shaped contacting portions EYE and 62F. The contacting portions EYE
and 62F each include two, spaced apart, flat, in-dined surfaces 62G and 62H, inclined at an angle of approximately 45 degrees to the plane of the lower slat section 62C and extending laterally across the inner surfaces ox the contacting potion EYE and 62F. A
stop 62J (Fig. 4) is provided for limiting the upward movement of the contact arm 66.
The contact arm 66 is fixedly secured to a rotatable pin 78 (Fig. 11) for rotation therewith within the curved contacting portions EYE and 62F
about the longitudinal axis of the rotatable pin 78.
The rotatable pin 78 includes outwardly extending round contacting portions AYE and 78B that art biased by the compression springs 68 into effective current conducting contact with the surfaces 62G and 62H
of the portions 62F end EYE, respectively. In this d I
11 51,006 manner effective conductive contact and current tray-suer is achieved between the lower formed stationary member 62 and the lower movable contact arm 66 through the rotatable pin 78. The lower movable con-tact arm 66 includes an elongated rigid lever arm 66Aextending between the rotatable pin 78 and the con-tact 72 and a downwardly protuberant portion or spring locator 66B for receipt within the upper end of the compression spring 70 for maintaining effect live contact between the lower movable arm 66 and the compression spring 70. Finally, the lower movable contact arm 66 includes an integrally formed, flat surface 66C formed at its lower end for contacting the stop 62J to limit the upward movement of the lower movable contact arm 66 and the contact 72 fixedly secured thereto The lower electrical contact 50 as desk cried hereinabove utilizes the high magnetic repel-soon forces generated by high level short circuit or fault current flowing through the elongated parallel portions of the electrical contacts 50 and 52 to cause the rapid downward movement of the contact arm 66 against the bias of the compression spring 70 twig. I An extremely rapid separation of the elect tribal contacts 50 and 52 and a resultant rapid increase in the resistance across the electrical arc formed between the electrical contacts 50 and 52 is thereby achieved, providing effective fault current limitation within the confines of relatively small physical dimensions. The lower electrical contact 50 further eliminates the necessity for utilizing flexible copper shunts used in many prior art molded case circuit breakers for providing a current carry-in conductive path between a terminal of the circuit breaker and a lower movable contact arm of a lower electrical contact. The use of the compression springs 68 to provide a constant bias against the pin 3 0 Old $
12 51,006 78 provides an effective current path between the terminal 38B and the contact 72 while enabling the mounting of the lower electrical contact 50 in a small, compact area.
The operating mechanism 58 includes an over-center toggle mechanism 80; a trip mechanism 82;
an integral or one-piece molded cross bar I (Fig.
12); a pair of rigid, opposed or spaced apart, metal side plates 86; a rigid, pivot able, metal handle yoke 88; a rigid stop pin 90; and a pair of operating ten-soon springs 92.
The over-center toggle mechanism 80 in-eludes a rigid, metal cradle 96 that it rotatable about the longitudinal central axis of a cradle sup-port pin 98. The opposite longitudinal ends of the cradle support pin 98 in an assembled condition are retained in a pair of apertures 100 formed through the side plates 86.
The toggle mechanism 80 further includes a pair of upper toggle links 102, a pair of lower tog-glue links 104, a toggle spring pin 106 and an upper toggle link follower pin 108. The lower toggle links lay are secured to thy upper electrical contact 52 by a toggle contact pin 110. Mach of the lower toggle links 104 includes a lower aperture 112 for receipt there through of the toggle contact pin 110. The tog glue contact pin 110 also passes through an aperture 114 formed through the upper electrical contact 52 enabling the upper electrical contact 52 to freely rotate about the central longitudinal axis of the pin 110. The opposite longitudinal ends of the pin 110 are received and retained in the cross bar 84. Thus, movement of the upper electrical contact 52 under other than high level short circuit or fault current conditions and the corresponding movement of the cross bar 84 is effected by movement of the lower toggle links 104. In this manner, movement of the I I
13 51,006 upper electrical contact 52 by the operating motion-sum 58 in the center pole or phase of the circuit breaker 30 simultaneously, through the rigid cross bar 84, causes the same movement in the upper elect tribal contacts 52 associated with the other poles or phases of the circuit breaker 30.
Each of the lower toggle links 1~4 also includes an upper aperture 116; and each of the upper toggle links 102 includes an aperture 118. The pin 106 is received through the apertures 116 and 118, thereby interconnecting the upper and lower toggle links 102 and 104 and allowing rotational movement there between. The opposite longitudinal ends of the pin 106 include journals 120 for the receipt and retention of the lower, hooked or curved ends 122 of the springs 92. The upper, hooked or curved ends 124 of the springs 92 are received through and retained in slots 126 formed through an upper, planar or flat surface 128 of the handle yoke 88~ At least one of the slots 126 associated with each spring 92 includes a locating recess 130 for positioning the curved ends 124 of the springs 92 to minimize or prevent sub Stan-trial lateral movement of the springs 92 along the lengths of the slots 126.
In an assembled condition, the disposition of the curved ends 1~4 within the slots 126 and the disposition of the curved ends 122 in the journals 120 retain the links 102 and 104 in engagement with the pin 106 and also maintain the springs 92 under tension, enabling tune operation of the over-center toggle mechanism 80 to be controlled by and respond size to external movements of the handle 42.
The upper links 102 also include recesses or grooves 132 for receipt in and retention by a pair of spaced apart journals 134 formed along the length of the pin 108~ The center portion of the pin 108 is configured to be received in an aperture 136 formed -- 14 51,006 through the cradle 96 at a location spaced by a pro-determined distance from the axis of rotation of the cradle 96. Spring tension from the springs 92 retains the pin 103 in engagement with the upper tog-glue links 102. Thus, rotational movement of the cradle 96 effects a corresponding movement or disk placement of the upper portions of the links 102.
The cradle 96 includes a slot or groove 14G
having an inclined flat latch surface 142 formed therein. The surface 142 is configured to engage an inclined flat cradle latch surface 144 formed at the upper end of an elongated slot or aperture 146 formed through a generally flat, intermediate latch plate 148. The cradle 96 also includes a generally flat handle yoke contacting surface 150 configured to con-tact a downwardly depending elongated surface 152 formed along one edge of the upper surface 128 of the handle yoke 88. The operating springs 92 move the handle 42 during a trip operation, and the surfaces 150 and 152 locate the handle 42 in a TRIPPED post-lion (Fig. 15), intermediate the CLOSE position (Fig. 3) and the OPEN position (Fig. 14) of the handle 42, to indicate that the circuit breaker 30 has tripped. In addition, the engagement of the surfaces 150 and 152 resets the operating mechanism 58 subset quint to a trip operation by moving the cradle 96 in a clockwise direction against the bias of the operate in springs 92 from its TRIPPED position (Fig. 15) to and past its OPEN position (Fig. 14) to enable the rematching of the surfaces 142 and 144.
The cradle 96 further includes a generally flat elongated stop surface 154 for contacting a peripherally disposed, radially outwardly protuberant portion or rigid stop 156 formed about the center of the stop pin 90. The engagement of the surface 154 with the rigid stop 156 limits the movement of the cradle 96 in a counterclockwise direction subsequent 51,006 to a trip operation (Fig. 15~. The cradle 36 also includes a curved, intermediate latch plate follower surface 157 for maintaining contact with the outer-most edge of the inclined latch surface 144 of the intermediate latch plate 148 upon the disengagement of the latch surfaces 142 and 144 during a trip open-anion (Fig. 15). An impelling surface of kicker 158 is also provided on the cradle 96 for engaging a radially outwardly projecting portion or contacting surface 160 formed on the pin 106 upon the release of the cradle 96 to immediately and rapidly propel the pin 106 in a counterclockwise arc from an OPEN post-lion (Fig. 3) to a TRIPPED position (Fig. 15), thereby rapidly raising and separating the upper electrical contact 52 from the lower electrical con-tact 50.
During such a trip operation, an enlarged portion or projection 162 formed on the upper toggle links 102 is designed to contact the stop 156 with a considerable amount of force provided by the operate in spring 92 through the rotating cradle I
thereby accelerating the arcuate movements of the upper toggle links 102, the toggle spring pin 106 and the lower toggle links 104. In this manner, the US speed of operation or the response time of the open cling mechanism 58 is significantly increased.
the trip mechanism 82 includes the inter-mediate latch plate 148, a movable or pivotabLe handle voice latch 166, a torsion spring spacer pin I 168, a double acting torsion spring 170, a molded, integral or one-piece trip bar 172 (Fig. 13), an arm-azure 174, an armature torsion spring 176, a magnet 178, a bimetal 180 and a conductive member or heater 182. The bimetal lay is electrically connected to the terminal 40B through the conductive member 182.
The magnet 178 physically surrounds the bimetal 180 thereby establishing a magnetic circuit Jo provide a 16 51,006 response to short circuit or fault current condo-lions. An armature stop plate 184 has a downwardly depending edge portion 186 that engages the upper end of the armature 174 to limit its movement in the counterclockwise direction. The torsion spring 176 has one longitudinal end formed as an elongated spring arm 188 for biasing the upper portion of the armature 174 against movement in a clockwise direct lion. An opposite, upwardly disposed, longitudinal end 190 of the torsion spring 176 is disposed in one of a plurality of spaced apart apertures (not thus-treated) formed through the upper surface of the plate 184. The spring tension of the spring arm 188 may be adjusted by positioning the end 190 of the torsion spring 176 in a different one ox the apertures formed through the upper surface of the support plate 184.
The bimetal 180 includes a formed lower end 192 spaced by a predetermined distance from the lower end of a downwardly depending contact leg 194 of the trip bar 172 (Fig. 3). The spacing between the end 192 and the let 194 when the circuit breaker 30 is in a CLOSED position (Fig. 3) may be adjusted to change the response time of the circuit breaker 30 to over-load conditions by appropriately turning a set screw 196, access to which may be provided by apertures 198 formed through the top cover 32. A current carrying conductive path between the lower end 192 of the bit metal 180 and the upper electrical contact 52 is achieved by a flexible copper shunt 200 connected by any suitable means, for example, by brazing, to the lower end 192 of the bimetal 180 and to the upper electrical contact 52 within the cross bar 84. In this manner, an electrical path is provided through the circuit breaker 30 between the terminals 38B and 40B via the lower electrical contact 50, the upper electrical contact 52, the flexible shunt 200, the bimetal 180 and the conductive member 182.

17 51,006 In addition to the cradle latch surface 144 formed at the upper en of the elongated slot 146, the intermediate latch plate 148 includes a generally square shaped aperture 210, a trip bar latch surface 212 at the lower portion of the aperture 210, an upper inclined flat portion 214 and a pair of oppo-Seattle disposed laterally extending pivot arms 216 configured to be received within inverted keystones or apertures 218 formed through the side plates 86.
The configuration of the apertures 218 is designed to limit the pivot able movement of the pivot arms 216 and thus of the intermediate latch plate 148.
The handle yoke latch 166 includes an aver-lure 220 for receipt there through of one longitudinal end 222 of the pin 168. The handle yoke latch 1~6 is thus movable or pivot able about the longitudinal axis of the pin 168. An opposite longitudinal end 224 of the pin 168 and the end 272 are designed to be no-twined in a pair of spaced apart apertures 226 formed through the side plates 86. Prior to the receipt of the end 224 in the aperture 226, the pin 168 is past sod through the torsion spring 170 to mount the ion-soon spring 170 about an intermediately disposed raised portion 228 of the pin 168. Owe longitudinal end of the body of the torsion spring 170 is received against an edge 230 of a raised portion 232 of the pin 168 to retain the torsion spring 170 in a proper operating position The torsion spring 170 includes an elongated, upwardly extending spring arm 234 for biasing the flat portion 214 of the intermediate latch plate 148 for movement in a counterclockwise direction for resetting the intermediate latch plate 148 subsequently to a trip operation by the over-center toggle mechanism 80 and a downwardly extending I spring arm 236 for biasing an upper portion or sun-face 237 of the trip bar 172 against rotational move-mint in a clockwise direction (Fig. 3).

18 51,006 The handle yoke latch 166 includes an eon-grated downwardly extending latch leg 240 and a bent or outwardly extending handle yoke contacting portion 242 (Figs. 9 and 12) that is physically disposed to be received in a slotted portion 244 formed in and along the length of one of a pair of downwardly de-pending support arms 246 of the handle yoke 88 during a reset operation (Fig. 14). The engagement of the aforementioned downwardly depending support arm 246 by the handle yoke latch 166 prohibits the handle yoke 88 from traveling to its reset position if the contacts 72 and 306 are welded together. If the con-teats 72 and 306 are not welded together, the cross-bar 84 rotates to its TRIPPED position (Fig. 15);
and the handle yoke latch 166 rotates out of the path of movement of the downwardly depending support arm 246 of the handle yoke 88 and into the slotted port lion 244 to enable the handle yoke 88 to travel to its reset position, past its OPEN position (Fig. 14).
An integrally molded outwardly projecting surface 248 on the cross bar 84 is designed to engage and move the latch leg 240 of the handle yoke latch 166 out of engagement with the handle yoke 88 during the move-mint of the cross bar 84 from its OPEN position (Fig.
14) to its CLOSED position (Fig. 3).
Preferably, the trip bar 172 is formed as a molded, integral or one-piece trip bar 172 having three, spaced apart downwardly depending contact legs 194, one such contact leg 194 being associate with each pole or phase ox the circuit breaker 30. In ad-diction, the trip Day 172 includes three, enlarged armature support sections 250, one such support sea-lion 250 for each pole or phase of the circuit breaker 30~ Each of the support sections 250 in-eludes an elongated generally rectangularly shaped slot or pocket 252 formed there through (Figs. 6 and 9) for receiving a downwardly depending trip leg 254 19 51,006 of the armature 174. The armature 174 includes out-warmly extending edges or shoulder portions 256 for enraging the upper surfaces of the pockets 252 to properly seat the armature 174 in the trip bar 172.
Each trip leg 254 is designed to engage and rotate an associated contact leg 194 of the trip bar 172 in a clockwise direction fig. 151 upon the occurrence of a short circuit or fault current condition.
The trip bar 172 also includes a latch sun-face 258 (Fig. 3) for engaging and latching the trip bar latch surface 212 of the intermediate latch plate 148. The latch surface 258 is disposed between a generally horizontally disposed surface 260 and a separate, inclined surface 262 of the trip bar 172.
The latch surface 258 (Fig. 3) is a vertically ox-tending surface having a length determined by the desired response characteristics of the operating mock-anise 58 to an overload condition or to a short air-cult or fault current condition. In a specific embodiment of the present invention, an upward move-mint of the surface 260 of approximately one-half millimeter is sufficient to unlatch the surfaces 258 and 212. Such unlatching results in movement between the cradle 96 and the intermediate latch plate 148 along the surfaces 142 and 144, immediately unlatch-in the cradle 96 from the intermediate latch plate 148 and enabling the counterclockwise rotational movement of the cradle 96 and a trip operation of the circuit breaker 30. During a reset operation, the spring arm 236 of the torsion spring 170 engages the surface 237 of the trip bar 172, causing the surface 237 to rotate counterclockwise to enable the latch surface 258 of the trip bar 172 to engage and rematch with the latch surface 212 of the intermediate latch plate 148 to reset the intermediate latch plate 148, the trip bar 172 and the circuit breaker 30. The length of the curved surface 157 of the cradle 96 I
51,00~
should be sufficient to retain contact between the upper portion 214 of the intermediate latch plate 148 and the cradle 96 to prevent resetting of the inter-mediate latch plate 148 and the trip bar 172 until 5 the latch surface 142 of the cradle 96 is positioned below the latch surface 144 of the intermediate latch plate 148. Preferably, each of the three poles or phases of the circuit breaker 30 is provided with a bimetal 180, an armature 174 an a magnet 178 for

10 displacing an associated contact leg 194 of the trip bar 172 as a result of the occurrence of an overload condition or of a short circuit or fault current con-diction in any one of the phases to which the circuit breaker 30 is connected.
In addition to the integral projecting surf face 248, the cross bar 84 includes three enlarged sections 270 (Fig. 12) separated by round bearing surfaces 272. A pair of peripherally disposed, out-warmly projecting locators 274 are provided to retain 20 the cross bar 84 in proper position within the base 36. The base 36 includes bearing surfaces 276 fig.
7) complimentarily shaped to the bearing surfaces 272 for seating the cross bar 84 for rotational movement in the base 34. The locators 274 are received within 25 arcuate recesses or grooves 278 formed along the sun-faces 276. Each enlarged section 270 further in-eludes a pair of spaced apart apertures 280 (Fig. 10) for receiving the toggle contact pin 110. The pin 110 may be retained within the apertures 280 by any 30 suitable means, for example, by an interference fit therebett~7een.
Each enlarged section 270 also includes a window, pocket or fully enclosed opening 282 formed therein fig. 12) for receipt of one longitlldinal end 35 or base portion 284 of the upper electrical contact 52 fig. 3). The opening 282 Allah permits the receipt and retention of a contact arm compression I
21 51,006 spring 28G (Fig. 12) and an associated, formed, spring follower 288. The compression spring 286 is retained in proper position within the enlarged sea-lion 270 by being disposed about an integrally formed, upwardly projecting boss 290.
The spring follower 288 is configured to be disposed between the compression spring 286 and the base portion 284 of the upper electrical contact 52 to transfer the compressive force from the spring 286 to the base portion 284, thereby ensuring that the upper electrical contact 52 and the cross bar 84 move in unison. The spring follower 288 includes a pair of spaced apart generally J-shaped grooves 292 formed therein for receipt of a pair of complimentarily shaped, elongated ridges or shoulder portions 294 to properly locate and retain the spring follower 288 in the enlarged section 270. A first generally planar portion 296 is located at one end of the spring folk lower 288; and a second planar portion 298 is located at the other longitudinal end of the spring follower 288 and is spaced from the portion 29~ by a generally flat inclined portion 300~
The shape of the spring follower 288 en axles it to engage the base portion 284 of the upper electrical contact 52 with sufficient spring force to ensure that the upper electrical contact 52 follows the movement of the cross bar 84 in response to operator movements of the handle 42 or the operation of the operating mechanism 58 during a normal trip operation. However, upon the occurrence of a high level short circuit or fault current condition, the upper electrical contact 52 can rotate about the pin 110 by deflecting the spring follower 288 downwardly fig. 3), enabling the electrical contacts 50 and 52 to rapidly separate and move to their BLOWN-OPEN pox sessions (Fig. 3) without waiting for the operating mechanism 58 to sequence. This independent movement 22 51,00~
of the upper electrical Contact 52 under the above high fault condition is possible in any pole or phase of the circuit breaker 30.
During normal operating conditions, an in-dined surface 302 of the base portion 284 of the upper electrical contact 52 contacts the inclined portion 300 or the junction between the portions 29~
and 300 of the spring follower 288 to retain the cross bar 84 in engagement with the upper electrical contact I However, upon the occurrence of a high level short circuit or fault current condition, the inclined surface 302 is moved past and out of engage-mint with the portions 298 and 300; and a terminal portion or surface 304 of the base portion 284 en-gages the downwardly deflected planar portion 298 of the spring follower 288 to retain the upper elect tribal contact 52 in its BLOWN-OPEN position, thereby eliminating or minimizing the possibility of contact restrike. Subsequently, when the circuit breaker 30 trips, the upper electrical contact 52 is forced by the operating mechanism 58 against the stop 156 to reset the upper electrical contact 52 for movement in unison with the cross bar 84. During this resetting operation, the surface 304 is moved out of engagement with the portion 298 and the inclined portion 302 is moved back into engagement with the spring follower 288. By changing the configuration of the spring follower 288 or the configuration of the surfaces 302, 304 of the base portion 284 of the upper elect tribal contact 52, the amount of upward travel of the upper electrical contact 52 during a aLOWN-OPEN open-anion required to bring the surface 304 into contact with the spring follower 288 can be altered as desired.
The openings 282 formed in the enlarged sections 270 of the cross bar 84 permit the passage of the flexible shunts 200 there through without I
23 51,006 significantly reducing the strength of the cross bar 84. Since the flexible shunts 200 pass through the openings 282 adjacent the axis of rotation of the cross bar 84, minimum flexing of the flexible shunts 200 occurs, increasing the longevity and reliability of the circuit breaker 30.
The upper electrical contact 52 also in-eludes a contact 306 for physically and electrically contacting the contact 72 of the lower electrical contact So and an upper movable elongated contact arm 308 disposed between the contact 306 and the base portion 284. It is the passage of high level short circuit or fault current through the generally penal-lot contact arms 66 and 308 that causes very high magnetic repulsion forces between the contact arms 66 and 308, effecting the extremely rapid separation of the contacts 72 and 306. on electrically insulating strip 309 may be used to electrically insulate the upper contact arm 308 from the lower contact arm 66.
In audition to the apertures 100, 218 and ~26, the side plates 86 include apertures 310 for the receipt and retention of the opposite ends of the stop pin 90. In addition, bearing or pivot surfaces 312 are formed along the upper portion of the side plates 86 for engagement with a pair of bearing sun-faces or round tabs 314 formed at the lowermost ox-tremities of the downwardly depending support arms 246 of the handle eye I The handle yoke 88 is thus controllable pivotal about the bearing surfaces 314 and 312, Tune side plates 86 also include bearing surfaces 316 (Figs. 7 and 12) for contacting the upper portions Ox tune bearing surfaces 272 of the cross bar 84 and or retaining the cross bar 84 securely in position within the base 34. The side plates 86 include generally C-shaped bearing surfaces 317 configured to engage a pair of round bearing sun-faces 318 disposed between the support sections 250 24 51,006 of the trip bar 172 for retaining the trip bar 172 in engagement with a plurality of retaining surfaces 320 (Fig. 5) integrally formed as part of the molded base 34. Each of the side plates 86 includes a pair of downwardly depending support arms 322 that terminate in elongated, downwardly projecting stakes or tabs 324 for securely retaining the side plates 86 in the circuit breaker 30. Associated with the tabs 324 are aperture metal plates 326 that are configured to be received in recesses 328 (Figs. 5, 7 and 8). In assembling the support plates 86 in the circuit breaker 30, the tabs 324 are passed through apertures formed through the base 34 and, after passing through the aperture metal plates 326, are positioned in the recesses 328. The tabs 324 may then be mechanically deformed, for example, by preening, to lock the tabs 324 in engagement with the aperture metal plates 326, thereby securely retaining the side plates 86 in engagement with the base 34. A pair ox formed elect tribally insulating barriers 3~9 (Figs. 5 through 8) is used to electrically insulate conductive combo-newts and surfaces in one pole or phase of the air-cult breaker 30 from conductive components or sun-faces in an adjacent pole or phase of the circuit breaker 30.
on operation the circuit breaker 30 may be interconnected in a three phase electrical circuit via line and load connections to the terminals AYE, B
and C and AYE, B and C. The operating mechanism 58 may be set by moving the handle 42 from its TRIPPED
position (Fig. 15) as far as possible past its OPEN
position (Fig. 14) to ensure the resetting of the intermediate latch plate 148, the cradle 96 and the trip bar 172 by the engagement of the latching sun-races 142 and 144 an by the engagement of the latch surfaces 212 and 258. The handle 42 may then be moved from its OPEN position (jig. 14) to its CLOSED

- 25 51,006 position (Fig. 3) causing the operating mechanism 58 to close the contacts 72 and 306; and the circuit breaker 30 is then ready for operation in protecting a three phase electrical circuit. If, due to a prior overload condition, the bimetal 180 remains heated and deflects the contact leg 194 of the trip bar 172 sufficiently to prevent the latching of the surface 212 with the surface 258, the handle 42 will return to its TRIPPED position (Fig. 15); and the electric-at contacts 50 and 52 will remain separated. After the bimetal 180 has returned to its normal operating temperature, the operating mechanism 58 may be reset as described above.
Upon the occurrence of a sustained overload condition, the formed lower end 192 of the bimetal 180 deflects along a clockwise arc and eventually de-floats the contact leg 194 of tune trip bar 182 surf-~iciently to unlatch the intermediate latch plate 148 from the trip bar 1~2, resulting in immediate rota-live movement between the cradle 36 and the inter mediate latch plate 148 along the inclined surfaces 142 and 144. The cradle 96 is immediately acceder-axed by the operating springs 92 for rotation in a counterclockwise direction (Fig. 3) resulting in the substantially instantaneous movement of the upper toggle links 102, the toggle spring pin 106 and the lower toggle links 104. As described hereinabove, the impelling surface or kicker 158 acting against the contacting surface 160 of the pin 106 rapidly accelerates the pin 106 in an upward, counter clock-wise arc, resulting in a corresponding upward move-mint of the toggle contact pin 110 and the immediate upward movement of the upper electrical contact 52 to its TRIPPED position (Fig. lo). Since the base port lions 284 of all of the upper electrical contacts 52 are biased by the springs 286 into contact with an interior surface 330 formed in each opening 282 of - I 51,006 the cross bar 84, the upper electrical contacts 52 move in unison with the cross bar 84, resulting in the simultaneous or synchronous separation of all three of the upper electrical contacts 52 from the lower electrical contacts 50 in the circuit breaker 30. During this trip operation, any electrical arc that may have been present across the contacts 72 and 306 is extinguished.
During this operation as a result of the change in the lines of action of the operating springs 92, the handle 42 is moved from its CLOSED
position (Fig. 3) to its TRIPPED position (Fig. 15).
As is apparent, if the handle 52 is obstructed or held in its CLOSED position (Fig. 3), the operating mechanism 58 still Jill respond to an overload condo-lion or to a short circuit or fault current condition to separate the electrical contacts 50 and 52 as de-scribed hereinabove. Furthermore, if the contacts 72 and 306 become welded together, the pin 106 does not move sufficiently to change the line of action of the operating springs 92 (Fig. 3), maintaining the operating springs 92 forward (to the left) of the pivot surfaces 312 of the side plates 86 and biasing the handle 42 to its CLOSED position so as no to mislead operating personnel as Jo the operative con-diction of the electrical contacts 50 and 52.
Upon the occurrence of a short circuit or fault current condition, the magnet 178 is imp mediately energized to magnetically attract the aroma-lure 174 into engagement with the magnet 178, result-in in a pivot able or rotational movement of the trip leg 254 of the armature 174 in a clockwise direction (Fig. 3) against the contact leg 194 of the trip jar 172. The resultant rotational movement of the con-tact leg 194 in a clockwise direction releases the intermediate latch plate 148 causing a trip operation as described hereinabove.

I

--- 27 51,006 Upon the occurrence of a high level short circuit or fault current condition and as a result of the large magnetic repulsion forces generated by the flow of fault current through the generally parallel contact arms 66 and 308, the electrical contacts 50 and 52 rapidly separate and move to their BLOWN-OPEN
positions (depicted in dotted line form in Fig. 3).
While the compression spring 70 returns the contact arm 66 of the lower electrical contact 50 to its OPEN
position (Fig. 14), the contact arm 308 is held in its BLOWN-OPEN position by the engagement of the sun-faces 304 and 298 as described hereinabove. The separation of the electrical contacts 50 and 52 is achieved without the necessity I the operating mechanism 58 sequencing through a trip operation.
However, the subsequent sequencing of the operating mechanism 58 through a trip operation forces the upper contact arm 308 against an electrical insular lion barrier 332 and the stop 156 in the center pole or phase of the circuit breaker 30 or against stops integrally formed in the top cover 32 in the outer poles or phases of the circuit breaker 30 to cause relative rotational movement between the upper elect tribal contact 52 and the cross bar 84, resulting in the preengagement of the interior surface 330 of the cross jar 84 by the base portion 284 of the upper electrical contact 52 and the resultant separation of the other electrical contacts 50 and 52 in toe other poles or phases of the circuit breaker 30.
In accordance with an alternative embossed-mint (Figs. 16 through 18) of the circuit breaker 30, an upper electrical contact 410 includes a longitude-net end or base portion 412 having a generally Jo shaped slot 414 formed therein. The slot 414 no-chives a portion of an elongated spring biased lock-in pin 416 that is disposed against the forward edges of a pair of elongated slots 418 formed through ~Ls~3~
I 51,006 a pair of opposed or spaced apart sidewalls 420 of an enlarged section 270 of the molded cross bar 84.
Preferably, an upper, outermost point or edge 422 of the slot 414 engages or contacts the outer periphery of the pin 416 at a distance less than halfway along the diameter of the pin 416 to ensure that upon the occurrence of a high level short circuit or fault cur rent of sufficient amperage, an upper, elongated move able contact arm 424 of the electrical contact 410 will be able to freely rotate about the pin 110 to assume a BLOWN-OPEN position (depicted in dotted line form in Fig. 16). Normally, the pin 416 is kept in engagement with the forward portion or surface of the slots 418 by a pair of tension springs 426 fixedly secured to the sidewalls 420 by a pair of spring pins 428. Thus, the pin 416 is at least partially received within the slot 414 to cause the movement of the cross bar 34 in unison with the movement of the upper electrical contact 410.
Upon the occurrence of a high level short circuit or fault current of sufficient amperage, the magnetic repulsion forces established by the flow of fault current through the generally parallel contact arms 66 and 424 are sufficient to move the contact edge 422 along the outer periphery of the pin 416~
resulting in a rearward displacement of the pin 416 against the force ox the tension springs 426. Fault currents of sufficient amperage can disengage the base portion 412 of the upper electrical contact 410 from the pin 416, thereby enabling the substantially unimpeded upward citation of the upper contact arm 424. A lower contact point or edge 430 is designed to downwardly deflect the free end of an elongated leaf sprint 432 secure to the base 34 by a fastener 434. After deflecting the leaf spring 432, the upper electrical contact 410 assumes its BLOWN OPEN post-lion (Fig. 16~. Subsequent kinetic between the 29 51,006 upper electrical contact 410 and the lower electrical contact 50 is prevented by the engagement of the free end of the leaf spring 432 with the base portion 412 in the region of the slot 414.
A subsequent trip operation of the operate in mechanism 58 lifts the upper electrical contact 410 from its BLOWN-OPEN position, removing the lock out feature of the leaf spring 432. During such a trip operation, the upper contact arm 424 is forced against the barrier 33~ and the stop 156 in the eon-ton pole or phase of the circuit breaker 30 or against stops integrally formed in the top cover 32 in the outer poles or phases of the circuit breaker 30 while the cross bar 84 is rotating in a clockwise direction, thus bringing the pin 416 into engagement with an inclined or contoured surface 436 of the base portion 412. By following along the contoured sun-face 436, the pin 416 is deflected rearwardly in the slot 418 until it passes the contact edge 42~ and snaps forward in the slot 414. In this manner, tune molded cross bar 84 and the upper electrical contact 410 are reset for subsequent normal movement in unit son.
In accordance with a further alternative embodiment figs. 19 trough 21) of the circuit breaker 30, an upper electrical contact 450 includes a longitudinal end or base portion 452 with an eon-grated stop pin 454 fixedly secured thereto and out-warmly projecting in opposite directions therefrom.
The stop pin 454 is positioned on the base portion 452 to engage and load an upper, elongated free end or spring arm 456 of one or more torsion springs 458~
An opposite, elongated lower end or spring arm 460 engages and is loaded by an interior lower surface 462 of the opening 282 formed in the molded cross bar 84. The torsion springs 458 are disposed and no-twined in position by a spring mounting pin 464 fixedly of - 30 51~006 secured in a pair of opposed or spaced apart sidewalls 466 of the cross bar 84. Thus, during nor-met operation, the stop pin 454 loads the spring arm 456 with a force at a distance relatively close to S the fulcrum of the torsion springs 458. In this man-nor, the upper electrical contact 450 is caused to move in unison with movements of the cross bar 84.
However, in the presence of a high level short air-cult or fault current of sufficient amperage, the no-pollution forces present as a result of the flow of fault current through the electrical contacts 50 and 450 cause the rapid separation of the electrical con-teats 50 and 450 prior to a trip operation of the operating mechanism 58. During such an occurrence, lo the stop pin 454 upon the clockwise rotation of the upper electrical contact 450 moves forwardly along the spring arm 456, increasing the distance between the location of the stop pin 454 and the fulcrum of the torsion springs 458, thereby decreasing the spring force applied by the spring arm 456 against the stop pin 454. However, the reduced spring force is sufficient to retain the upper electrical contact 450 in its BLOWN-OPEN position depicted in dotted line form in Fig. 19). During a trip operation by the operating mechanism 58, the upper electrical con-tact 450 is forced against the beefier 332 and the stop 156 during a clockwise rotational movement of the cross bar So, causing the consequent rearward movement of the stop pin 454 along the spring arm 456, decreasing the distance between the stop pin 454 and the fulcrum of each torsion spring 458 and no-establishing the normal spring load between the stop pin 454 and the spring arm 456. The upper electrical contact 450 and the cross bar 84 are thus reset for movement in unison.
In accordance with another alternative em-bodiment (Fits. 22 through 24) of the circuit ~3q~

31 51,006 breaker 30, an adjustable, stationary, lower electric eel contact 470 includes an integral or one-piece formed copper contact 472 and a separately formed, spacer bracket 474 formed from a material having sign nificantly less conductivity than copper, for exam-pie, steel. Extending outwardly from the base 34 is an integrally formed portion of the copper contact 472 that forms the first electrical terminal or the line terminal 38B. The formed copper contact 472 also includes an integral, inclined surface AYE come elementarily shaped to an inclined interior surface of the base 34 for engagement therewith. An inter-ally formed base portion 472B is positioned in a no-cuss 476 (Fig. 23) formed along the interior bottom surface of the base 34 for locating the lower elect tribal contact 470 in its proper position in the base 34. The formed copper contact 472 also includes an integrally formed, elongated stationary contact arm 472C that supports near its upper end a contact 72 fixedly secured thereto, for example by brazing.
The spacer bracket 474 includes an in~egr-ally formed base portion AYE supported above the base portion 472D by a plurality of integrally formed, delectable legs 474~. An integrally formed, upstanding spacer leg 474~ extends from the base pro lion AYE to an integrally formed, copper contact support portion 474D. The copper contact support portion 474D is fixedly secured to the underside of the upper end of the contact arm 472C Dye any suitable means, for example, by a rivet or by brazing.
Preferably, the deflectable legs 474B are positioned on and in contact with a raised shoulder portion 478 that extends upwardly from the interior bottom surface of the base 34. An aperture 480 is formed through the base portion 472B in line with both an aperture 482 formed through the bottom sun-face of the base 34 and a threaded aperture 48q ~3~J~
- 32 51,006 formed through the base portion AYE. The aligned apertures 480~ 482 an 484 receive a mounting screw 486 that secures the lower electrical contact 470 in its position in the base 34 and that adjusts the Yen-tidal height of the contact 72 above the base 34. By tightening the mounting screw 486, the legs 474B de-float to reduce the space between the base portions 472B and AYE, thereby lowering the copper contact support portion 474D and the longitudinal end of the stationary contact arm 472C fixedly secured thereto.
Thus, by tightening or loosening the mount-in screw 486, the vertical distance between the con-tact 72 and the base 34 can be precisely adjusted without the use of shims or trial and error proved-uses commonly resorted to in the prior art. In add-lion, after determining the desired amount of over-travel of the upper electrical contact 52, the subset quint precise adjustment of the lower electrical con-tact 470 in each pole or phase of the circuit breaker 30 results in less work being required to place the circuit breaker 30 in its CLOSED position, reducing the required size of and the stress on the operating springs 92 and the force required to move the handle 42 from its OPEN position to its CLOSED position.
The adjustable lower electrical contact 470 also per-mitt the contact pressure between the contacts 72 and 406 to be increased for higher current ratings with out changing the operating springs 92.
While the lower electrical contact 470 is stationary in operation, blow apart capability of the electrical contacts 52 and 470 is present due to the configuration of the formed copper contact 472 that provides parallel current paths in the contacts 52 and 470, resulting in high magnetic repulsion forces upon the occurrence of a high level short circuit or fault current condition. Upon such a condition, the electrical contact 52 will rapidly separate from the I
33 51,006 electrical contact 470 and assume its BLOWN-OPEN pox session (Fig. 3). The slot motor 56 may be utilized to achieve rapid separation of the contacts 52 and 470.
In accordance with another alternative em-bodiment twigs. 25 and 26) of the circuit breaker 30, a stationary lower electrical contact 490 in-eludes an integral or one-piece formed copper contact 492 supported in the base 34 by a support bracket 494, preferably formed from a material of Saigon-gently less electrical conductivity than copper, such as steel. The formed copper contact 472 includes an integrally formed portion extending exteriorly of the interior of the base 34 that forms the first terminal or line terminal 38B. The formed copper contact 492 also includes an upwardly extending inclined surface AYE and a contact mounting or support surface 492B
that also functions as an arc runner to transfer an electrical arc formed between the separating upper and lower electrical Contacts 52 and 490 to the arc chute 54. A contact 72 is fixedly secured to the support surface 492B by any suitable means, for example, by brazing. The support t bracket 494 includes a lower base portion AYE, a pair of positioning or support legs 494~ and a pair of integrally formed, upwardly extending support arms 494C that include up-warmly projecting tubs 494D extending upwardly from the support arms 494C. The tabs 494D are configured to be received within a pair of complimentarily shape Ed aperture 496 okayed through the support surface 492B. When the tabs 494D are inserted through top apertures 496, the tabs 494D are spun over or preened to fixedly secure the formed copper contact 492 in engagement with the support bracket 434. A threaded aperture 498 is formed through the base portion AYE
and is aligned with an aperture 500 formed through the bottom surface of the base 34 when the outermost I

- 34 51,~06 edges or surfaces of the support legs 494B are post-toned in engagement with the locating surfaces 502 integrally formed along the bottom surface of the base 34. A threaded mounting screw 504 is received in the aperture 500 and thirdly engages the aver-lure 498 to securely retain the stationary lower electrical contact 490 in engagement with the base 34.
The stationary lower electrical contact 490 may be u Ed in molded case circuit breakers 30 having lower current ratings than those of the other embody-mints of the circuit breaker 30 discussed above and where blow-open capability of the circuit breaker 30 is not required. As is apparent from the configure-lion of the lower electrical contact 490, a parallel current path between elongated portions of the elect tribal contacts 52 and 490 does not exist; and, thus, the large magnetic repulsion forces discussed herein-above with respect to the other embodiments of the circuit breaker 30 are not generated.
Obviously, many modifications and vane-lions of the present invention are possible in light ox the above teachings. Thus it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specie focally described hereinabove.

Claims (15)

Claims:

1. An electrical circuit breaker comprising:
first and second separable electrical contacts, said first electrical contact having a base portion disposed at one longitudinal end thereof with said base portion includ-ing a slot formed herein, and operating means for opening and closing said first and second electrical contacts, said operating means comprising an elongated rotatable member and spring means for enabling both the rotational movement of said first electrical contact in unison with said elongated member and the rotational move-ment of said first electrical contact independently of rotation of said elongated member, said spring means comprising a first tension spring, a locking pin biased by said first tension spring, and a second tension spring biasing said pin, said first tension spring and said second tension spring being secured to said pin at opposite longitudinal ends thereof, said pin being receivable within said slot for enabling the rotational movement of said first electrical contact in unison with said elongated member, said slot and said pin being physically configured to effect the removal of said pin from said slot upon the occur-rence of a high level short circuit or fault current condition for enabling the rotational movement of said first electrical contact independently of rotation of said elongated member.

2. An electrical circuit breaker as recited in claim 1 wherein said elongated member includes an elongated aperture formed therein, said pin being disposed in said aperture and being biased into contact with an end of said aperture by said tension springs.

3. An electrical circuit breaker as recited in claim 1 further comprising latching means for maintaining said first electrical contact spaced apart from said second electrical contact subsequently to said rotational movement of said first electrical contact independently of said elon-gated member.

4. An electrical circuit breaker comprising:
first and second separable electrical contacts, said first electrical contact having a base portion disposed at one longitudinal end thereof with said base portion including a slot formed therein, operating means for opening and closing said first and second electrical contacts, said operating means comprising an elongated rotatable member and spring means for enabling both the rotational movement of said first electrical contact in unison with said elongated member and the rotational move-ment of said first electrical contact independently of rotation of said elongated member, said spring means comprising a tension spring and a locking pin biased by said tension spring, said pin being receivable within said slot for enabling the rotational movement of said first electrical contact in unison with said elongated member, and latching means for maintaining said first electrical contact spaced apart from said second electrical contact subse-quently to said rotational movement of said first electrical contact independently of rotation of said elongated member, said latching means comprising a leaf spring having one longi-tudinal end fixedly secured in said circuit breaker and having an opposite longitudinal end positioned in said circuit breaker for deflection and release by said base portion during said rotational movement of said first electrical contact independ-ently of rotation of said elongated member, said opposite longitudinal end being disposed in said circuit breaker to limit the movement of said first electrical contact subsequent-ly to being deflected by said base portion.

5. An electrical circuit breaker as recited in claim further comprising a molded case formed from electri-cally insulating material within which said first and second electrical contacts and said operating means are disposed.

6. An electrical circuit breaker comprising:
a first movable electrical contact having a base portion and a first slot formed in said base portion, a second electrical contact and operating means for moving said first and second electrical contacts into a CLOSED position and into an OPEN
position, said operating means comprising a rotatable cross bar, said operating means further including spring means for enabling both the rotational movement of said first elec-trical contact in unison with said cross bar and the rotational movement of said first electrical contact independently of rotation of said cross bar, said spring means comprising a spring biased locking pin at least partially disposed in said first slot in contact with said base portion at some portion thereof along the periphery of said first slot, said pin capable of being removed from within said first slot, said cross bar including an elongated second slot formed therein, said pin being disposed in said second slot.

7. An electrical circuit breaker as recited in claim 6 wherein said spring means further comprises a tension spring for biasing said locking pin against one longitudinal end of said second slot.

8. An electrical circuit breaker as recited in claim 7 wherein said first slot and said pin are physically configured to effect the removal of said pin from said first slot upon the occurrence of a high level short circuit or fault current condition for enabling said rotational movement of said first electrical contact independently of said cross bar.

9. An electrical circuit breaker as recited in claim 7 wherein said spring means further comprises a second tension spring biasing said pin, said first mentioned tension spring and said second tension spring being secured to said pin at spaced apart locations along the length of said pin

10. An electrical circuit breaker comprising:
a first movable electrical contact having a base portion and a first slot formed in said base portion, a second electrical contact, operating means for moving said first and second electrical contacts into a CLOSED position and into an OPEN
position, said operating means comprising a rotatable cross bar, said operating means further including spring means for enabling both the rotational movement of said first elect-tribal contact in unison with said cross bar and the rotational movement of said first electrical contact independently of rotation of said cross bar, said spring means comprising a spring biased locking pin at least partially disposed in said first slot in contact with said base portion at some portion thereof along the periphery of said first slot, said pin cap-able of being removed from within said first slot, and latching means for maintaining said first electrical contact spaced apart from said second electrical contact sub-sequently to said rotational movement of said first electrical contact independently of rotation of said cross bar, said latching means comprising a leaf spring having one longitudinal end positioned in said circuit breaker for deflection by said base portion during said rotational movement of said first electrical contact independently of rotation of said cross bar.

11. An electrical circuit breaker as recited in claim 10 wherein said leaf spring is disposed in said circuit breaker to limit the movement of said first electrical contact subsequently to being deflected by said base portion.

12. An electrical circuit breaker comprising:
a first movable electrical contact having a slot formed therein;
a second electrical contact; and spring means for biasing said first electrical con-tact, said spring means comprising:

a spring biased locking pin at least partially disposed in said slot in contact with said first contact at some portion thereof along the periphery of said slot, said pin capable of being removed from within said slot;
a first tension spring biasing said locking pin; and a second tension spring biasing said pin, said first tension spring and said second tension spring being secured to said pin at spaced apart locations along the length of said pin.

13. An electrical circuit breaker as recited in claim 12 wherein said slot and said pin are physically con-figured to effect the removal of said pin from said slot upon the occurrence of a high level short circuit or fault current condition.

14. An electrical circuit breaker comprising:
a first movable electrical contact having a slot formed therein, a second electrical contact, spring means for biasing said first electrical con-tact, said spring means comprising a spring biased locking pin at least partially disposed in said slot in contact with said first contact at some portion thereon along the periphery of said slot, said pin capable of being removed from within said slot, and latching means for maintaining said first electrical contact spaced apart from said second electrical contact, said latching means comprising a leaf spring having one longitudinal end positioned in said circuit breaker for deflection by said first electrical contact.

15. An electrical circuit breaker as recited in claim 14 wherein said leaf spring is disposed in said circuit breaker to limit the movement of said first electrical contact subsequently to being deflected by said first electrical contact.